In the construction of semiconductor chips, it may be necessary to bond two or more substrates together. Conventional methods of bonding require the application of a bonding material or an adhesive layer between two substrates, such as wafers, and then curing of the bonding material. Upon curing, the properties of the bonding material enable the first and second wafers to be joined and secured together. While the use of a bonding material to bond the first and second wafers provides a relatively inexpensive form of bonding, such use presents at least one major drawback. Air often gets trapped in the bonding material, such that pockets of air or voids are created within the bonding material. This causes the thickness of the adhesive to vary at certain points along the respective wafers. Air voids present within the wafer will provide for a thicker adhesive material on one portion of the wafer as compared to another portion of the wafer where the bonding material may be nonexistent. As a result, the bond strength across all chips in the wafer is not uniform, with the bond strength being less where the voids are present. Moreover, the overall bond between the bonding material and wafer is therefore reduced.
Various methods have been devised to improve upon these shortcomings. Nevertheless, despite all of the effort which has been devoted to improving bonding, there are unmet needs for further improvements.